Re: In/into

: : Is it 'Police open fire in the air' or 'Police open fire into the air'.

: 'In' is best for me.
: However, the sentence has a most unusual construction. 'Police openED fire in ...' or 'Police are firing in ...' would be more normal in British English.

I on the other hand prefer "into". "Into" always expresses motion towards, whereas "in" is less specific, and often means "from the location of". Compare

"He pulled out his pistol and fired in the car".

versus

"He pulled out his pistol and fired into the car".

When I first read the phrase suggested by the original poster (police open fire in the air), thoughts of levitating law enforcement operatives were what instantly sprang to mind. However, I suspect there's no definitive right answer and that it does come down to personal preference.